<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <div class="list" style="display:flex ; text-align:center;">

    </div>
    <button class="prev">上一页</button>
    <button class="next">下一页</button>
    <script>

        var page = 1;
        function objToSearchString(obj) {
            var str = '';
            for (var key in obj) {
                str += `${key}=${obj[key]}&`
            }
            return str.slice(0, str.length - 1);
        }

        function ajax(method, url, params, cb) {
            var xhr = new XMLHttpRequest();
            xhr.open(method, url + "?" + objToSearchString(params));
            xhr.onreadystatechange = function () {
                if (xhr.readyState == 4) {
                    cb(JSON.parse(xhr.responseText));
                }
            }
            xhr.send();
        }
        if (page = 1) {
                ajax('get', `https://yantianfeng.com/api/emotion`, { page: 1, count: 10 }, function (data) {
                    // console.log(data);
                    var str = data.emotions.map((item, index) => {
                        return `<div> <img src="${item.url}" /> <div> ${item.title} </div> </div>`
                    }).join('')
                    document.querySelector('.list').innerHTML = str;
                });
            }
        document.querySelector('.prev').onclick = function () {
            if (page > 1) {
                ajax('get', `https://yantianfeng.com/api/emotion`, { page: --page, count: 10 }, function (data) {
                    // console.log(data);
                    var str = data.emotions.map((item, index) => {
                        return `<div> <img src="${item.url}" /> <div> ${item.title} </div> </div>`
                    }).join('')
                    document.querySelector('.list').innerHTML = str;
                });
            }
        }
        document.querySelector('.next').onclick = function () {
            if (page < 4) {
                ajax('get', `https://yantianfeng.com/api/emotion`, { page: ++page, count: 10 }, function (data) {
                    // console.log(data);
                    var str = data.emotions.map((item, index) => {
                        return `<div> <img src="${item.url}" /> <div> ${item.title} </div> </div>`
                    }).join('')
                    document.querySelector('.list').innerHTML = str;
                });
            }
        }  
    </script>
</body>

</html>